WO2018218936A1

WO2018218936A1 - Pixel circuit, driving method therefor, and display panel

Info

Publication number: WO2018218936A1
Application number: PCT/CN2017/117178
Authority: WO
Inventors: 王鹏鹏; 董学; 王海生; 丁小梁; 刘英明
Original assignee: 京东方科技集团股份有限公司
Priority date: 2017-06-02
Filing date: 2017-12-19
Publication date: 2018-12-06
Also published as: US20190279566A1; CN107204172B; US10810936B2; CN107204172A

Abstract

A pixel circuit, a driving method therefor, and a display panel. The pixel circuit (100) comprises a light-emitting component (110), a light emission control circuit (120), and a photoelectric sensing circuit (130). The light emission control circuit (120) is configured to drive the light-emitting component (110) to emit a light and comprises a first end (a1), a second end (a2), and a third end (a3). The first end (a1) is used for connecting to a first power supply end (V1); the second end (a2) is used for connecting to the light-emitting component (110). One end (c1) of the light-emitting component (110) is used for connecting to the second end (a2) of the light emission control circuit (120); the other end (c2) is used for connecting to a second power supply end (V2). The photoelectric sensing circuit (130) is configured to sense a light shone thereon and comprises a sensing signal output end (b1) and a sensing voltage input end (b2). The sensing voltage input end (b2) is used for connecting to the second power supply end (V2). The sensing signal output end (b1) is used for connecting to the third end (a3) of the light emission control circuit (120). The photoelectric sensing circuit (130) in the pixel circuit (100) allows the time-division multiplexing of the light emission control circuit (120) to generate a constant current, thus implementing high-precision sensing electric signal detection and, at the same time, optimizing the structural layout of the pixel circuit (100).

Description

Pixel circuit and driving method thereof, display panel

The present application claims priority to Chinese Patent Application No. 20171040768, filed on Jun. 2,,,,,,,,,,,,,,

Technical field

Embodiments of the present disclosure relate to a pixel circuit and a driving method thereof, and a display panel.

Background technique

Organic Light Emitting Diode (OLED) display panels have attracted widespread attention due to their advantages of wide viewing angle, high contrast ratio, fast response, high luminance, low driving voltage and flexible display. As a new generation of display methods, OLED display panels are widely used in electronic products such as mobile phones, computers, full-color TVs, digital video cameras, and personal digital assistants.

With the rapid development of display technology, electronic devices with biometric functions have gradually entered people's lives, and fingerprint recognition technology has received much attention because of its unique identity. At present, the push-type and sliding fingerprint recognition technologies based on the silicon-based process are gradually integrated into various electronic products, and the OLED display panel with fingerprint recognition function has also become a research hotspot of the display panel.

Summary of the invention

At least one embodiment of the present disclosure provides a pixel circuit including: a light emitting element, an illumination control circuit, and a photo sensing circuit. The illumination control circuit is configured to drive the light emitting element to emit light and includes a first end, a second end, and a third end, the first end for connecting to a first power end, and the second end for The light emitting element is connected; one end of the light emitting element is connected to the second end of the light emitting control circuit, and the other end is connected to the second power end; the photoelectric sensing circuit is configured to sense incident And the sensing voltage input end is configured to be connected to the second power end, and the sensing signal output end is configured to be connected to the light emitting control circuit Three-terminal connection.

At least one embodiment of the present disclosure also provides a display panel including an array of pixel units. At least one of the pixel units includes the pixel circuit of any of the above.

At least one embodiment of the present disclosure further provides a driving method of a pixel circuit according to any one of the above, comprising: in a display stage, the light emission control circuit drives the light emitting element to emit light; in the photoelectric sensing stage, from the The third end of the illumination control circuit outputs a predetermined current to the photo-sensing circuit, and then reads an output signal of the photo-sensing circuit.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It is obvious that the drawings in the following description relate only to some embodiments of the present disclosure, and are not to limit the disclosure. .

1 is a schematic diagram of a planar circuit of an optical fingerprint recognition device;

2a is a schematic block diagram of a pixel circuit according to an embodiment of the present disclosure;

2b is a schematic circuit diagram of a pixel circuit according to an embodiment of the present disclosure;

2c is a schematic circuit diagram of still another pixel circuit according to an embodiment of the present disclosure;

3a is a schematic circuit diagram of a photoelectric sensing circuit according to an embodiment of the present disclosure;

FIG. 3b is a schematic circuit diagram of still another photoelectric sensing circuit according to an embodiment of the present disclosure; FIG.

4a is a schematic circuit diagram of an illumination control circuit according to an embodiment of the present disclosure;

FIG. 4b is a schematic circuit diagram of still another illumination control circuit according to an embodiment of the present disclosure; FIG.

5a-5d are operational flow of the compensation method of the illumination control circuit shown in FIG. 4b;

FIG. 6 is a schematic plan view of a display panel according to an embodiment of the present disclosure; FIG.

6b is a schematic block diagram of a pixel unit of a display panel according to an embodiment of the present disclosure;

FIG. 7 is a cross-sectional structural diagram of a pixel unit of a display panel according to an embodiment of the present disclosure;

FIG. 8 is a flowchart of a driving method of a pixel circuit according to an embodiment of the present disclosure;

FIG. 9 is a schematic circuit diagram of still another pixel circuit according to an embodiment of the present disclosure;

Fig. 9b is an exemplary timing chart of the driving method of the pixel circuit shown in Fig. 9a.

detailed description

The technical solutions of the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings. It is apparent that the described embodiments are part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the described embodiments of the present invention without departing from the scope of the invention are within the scope of the invention.

Unless otherwise defined, technical terms or scientific terms used in the present disclosure are intended to be in the ordinary meaning of those of ordinary skill in the art. The words "first," "second," and similar terms used in the present disclosure do not denote any order, quantity, or importance, but are used to distinguish different components. Similarly, the words "a", "an", "the" The word "comprising" or "comprises" or the like means that the element or item preceding the word is intended to be in the The words "connected" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to indicate the relative positional relationship, and when the absolute position of the object to be described is changed, the relative positional relationship may also change accordingly.

In order to keep the following description of the embodiments of the present disclosure clear and concise, the present disclosure omits detailed descriptions of known functions and known components.

Fingerprint recognition technologies mainly include capacitive, ultrasonic, and optical technologies. The optical fingerprint recognition technology uses optical detection to detect and recognize the electrical signal obtained by the conversion of the optical signal, and has the advantages of high sensitivity, good stability, long service life and long distance sensing. The organic light emitting diode display panel having the fingerprint recognition function can adopt, for example, an optical fingerprint recognition technology.

Figure 1 shows a schematic diagram of a planar circuit of an optical fingerprinting device.

For example, as shown in FIG. 1, the optical fingerprinting device includes a plurality of scanning lines, a plurality of reading lines, and a plurality of photo sensing circuits 9 arranged in an array, each of the photo sensing circuits 9 being located in one sub-pixel. Here, the photoelectric sensing circuit 9 employs a passive detection method. For example, each of the photo-sensing circuits 9 includes a photodiode 90 for converting an optical signal into a sensing electrical signal, and an output transistor 91 for controlling the output of the sensing electrical signal generated by the photodiode 90. To the read line. One end of the photodiode 90 is connected to the power supply voltage terminal Vd, and the other end is connected to the first pole of the output transistor 91; the control electrode of the output transistor 91 is connected to a scan line to receive the scan control signal, and the second pole of the output transistor 91 is A read line connection.

For example, the specific process of fingerprint recognition may be: in the light accumulation stage, the light source is irradiated onto the finger, the finger reflects the incident light, the reflected light is irradiated onto the photodiode 90, and the photodiode 90 converts the light signal of the reflected light. For the sensing electrical signal corresponding to the intensity of the optical signal, since the geometric features of the ridge line and the valley line of the fingerprint are different, the ridge line is convex and the valley line is concave, so when they are illuminated by light, the light is The reflection intensity is also different, resulting in different sensing electrical signals outputted by the photodiodes 90 at different positions; in the output phase, the control terminal of the output transistor 91 receives the turn-on signal of the scan line transmission, and the output transistor 91 is turned on in turn. Therefore, the read line can sequentially read out the sensing electrical signals generated by the respective photodiodes 90, and by detecting the size of each sensing electrical signal, the detection of the fingerprint valley can be realized, thereby realizing fingerprint recognition.

Since the sensing electrical signal generated by the photodiode 90 is small, the passive photoelectric sensing circuit 9 has limited detection capability, high detection difficulty, low accuracy of the detected sensing electrical signal, and low signal to noise ratio. In addition, the read line is connected to a column of photodiodes 90 such that the sensed electrical signals output by all the photodiodes 90 of each column interfere with each other, affecting the detection accuracy.

At least one embodiment of the present disclosure provides a pixel circuit, a driving method thereof, and a display panel. The pixel circuit includes a light emitting element, a light emitting control circuit, and a photoelectric sensing circuit. The illumination control circuit is configured to drive the light emitting element to emit light and includes a first end, a second end and a third end, the first end of which is for connecting with the first power end, and the second end of the second end for connecting with the light emitting element; One end is connected to the second end of the illumination control circuit, and the other end is connected to the second power end; the photo sensing circuit is configured to sense the light incident thereon and includes the sensing signal output end and the induced voltage access The sensing voltage access terminal is configured to be coupled to the second power terminal, and the sensing signal output terminal is configured to be coupled to the third terminal of the lighting control circuit.

In at least one embodiment of the present disclosure, the photoelectric sensing circuit in the pixel circuit adopts an active detection method, and time-multiplexes the constant current generated by the illumination control circuit, thereby realizing high-precision sensing electrical signal detection and improving sensing power. The signal-to-noise ratio of the signal; in addition, at least one embodiment of the present disclosure can simultaneously reduce the space occupied by the photo-sensing circuit, optimize the structural layout of the pixel circuit, save manufacturing costs, and increase the added value of the product.

For example, according to the characteristics of the transistor, the transistor can be divided into an N-type transistor and a P-type transistor. For the sake of clarity, the embodiment of the present disclosure elaborates the technical solution of the present disclosure by taking a transistor as a P-type transistor as an example, but the implementation of the present disclosure. The transistor of the example is not limited to a P-type transistor, and those skilled in the art can also implement the function of one or more transistors in the embodiments in the present disclosure by using an N-type transistor according to actual needs.

It should be noted that the transistor used in the embodiment of the present disclosure may be a thin film transistor or a field effect transistor or other switching device with the same characteristics, and the source and the drain of the transistor may be symmetric in structure, so the source thereof The drain can be indistinguishable in physical structure. In the embodiment of the present disclosure, in order to distinguish the transistor from the gate as the gate, one of the first poles and the other pole are directly described. Therefore, the first pole of all or part of the transistors in the embodiment of the present disclosure. The second pole is interchangeable as needed. For example, for an N-type transistor, the first pole of the transistor can be the source and the second pole can be the drain; or, for the P-type transistor, the first extreme drain of the transistor and the second source of the second.

The pixel circuit and the driving method thereof and the display panel according to the present disclosure will be described below by way of several embodiments, but the present disclosure is not limited to these specific embodiments.

An embodiment of the present disclosure provides a pixel circuit.

For example, as shown in FIG. 2a and FIG. 2b, the pixel circuit 100 provided by the embodiment of the present disclosure may include a light emitting element 110 (for example, may be the light emitting element EL shown in FIG. 2b), an illumination control circuit 120, and a photo sensing circuit 130. The pixel circuit 100 provided by the embodiment of the present disclosure can be applied to, for example, a display panel such as an active matrix organic light emitting diode (AMOLED) display panel or the like.

For example, the specific structure of the light-emitting element 110, the light-emitting control circuit 120, and the photoelectric-sensing circuit 130 may be set according to actual application requirements, which is not specifically limited in the embodiment of the present disclosure. For example, a pixel circuit 100 provided by an embodiment of the present disclosure may be implemented as a circuit structure as shown in FIG. 2b.

For example, as shown in FIG. 2b, the light emitting element 110 is configured to emit light under application of a voltage or current, and the first end c1 of the light emitting element 110 is for connection with the second end a2 of the light emission control circuit 120, the second end C2 is used to connect to the second power terminal V2. The light emitting element 110 may be an organic light emitting element, and the organic light emitting element may be, for example, an organic light emitting diode, but embodiments of the present disclosure are not limited thereto. The light-emitting element 110 may, for example, use different luminescent materials to emit light of different colors to perform color illuminating.

For example, in one example, as shown in Figures 2a and 2b, pixel circuit 100 can also include signal line 140. The signal line 140 is arranged to receive and read the sensing electrical signal output by the sensing signal output terminal b1 of the photoelectric sensing circuit 130.

For example, in one example, as shown in FIG. 2c, on the basis of FIG. 2b, the pixel circuit 100 may further include a signal read switch circuit 160. When the plurality of photoelectric sensing circuits 130 share one signal line 140, the signal reading switch circuit 160 can control the signal line 140 to read the sensing electrical signals output by the single photoelectric sensing circuit 130 to prevent the sensing of the output of the respective photoelectric sensing circuits 130. The electrical signals interfere with each other, reducing noise and ensuring the signal-to-noise ratio of the sensed electrical signal.

For example, as shown in FIG. 2c, the signal line 140 includes a first portion 141 and a second portion 142, and the signal read switch circuit 160 is disposed between the first portion 141 and the second portion 142 and is configured to control the first portion 141 and the first portion The two portions 142 are turned on or off, and the first portion 141 is used to connect to the sensing signal output terminal b1 of the photo sensing circuit 130. For example, the signal read switch circuit 160 includes a signal read switch transistor M10, and the control electrode of the signal read switch transistor M10 can receive the first output signal EM1, and the signal reads the one end of the first and second portions 142 of the switch transistor M10. The other end of the second portion 142 is connected to a touch chip (not shown), for example, the second electrode of the signal read switch transistor M10 is connected to one end of the first portion 141, and the other end of the first portion 141 is connected to the photo sensing circuit 130. The sensing signal output terminal b1 is connected.

For example, the third end a3 of the illumination control circuit 120 is connected to the sensing signal output terminal b1 of the photo-sensing circuit 130, and the signal line 140 is configured to be connected to the third terminal a3 and the sensing signal output terminal b1. Therefore, in the touch detection and/or fingerprint recognition stage, the third end a3 of the illumination control circuit 120 can input a constant and controllable predetermined current to the sensing signal output terminal b1 of the photoelectric sensing circuit 130, so that the photoelectric sensing circuit 130 The sensing electrical signal is output to the sensing signal output terminal b1, and then the sensing electrical signal is read via the signal line 140 to implement touch detection or fingerprint recognition; or, in the display phase, the second end of the light control circuit 120 A2 may input a light-emission current signal corresponding to the light-emission data voltage to the light-emitting element 110 for realizing the light-emitting display. Therefore, the photoelectric sensing circuit 130 can time-multiplex the constant current generated by the light-emitting control circuit 120, realize high-precision sensing electrical signal detection, and improve the signal-to-noise ratio of the sensing electrical signal; that is, in the photoelectric sensing phase, the illumination control Circuit 120 can be equivalent to a current source. The pixel circuit can also reduce the space occupied by the photoelectric sensing circuit at the same time, optimize the structural layout of the pixel circuit 100, save manufacturing costs, and increase the added value of the product.

For example, the photo-sensing circuit 130 provided by the embodiment of the present disclosure will be described in detail below with reference to FIGS. 3a and 3b.

For example, the photoelectric sensing circuit 130 is configured to sense the intensity of the light incident thereon, and the generated sensing electrical signal can be used to determine whether there is a touch action, and can also be used to implement fingerprint recognition. For example, the photo-sensing circuit 130 is configured to determine whether there is a touch action by sensing the intensity of light emitted by the light source module (eg, the light-emitting element 110) to which the touch-operated finger or the stylus is reflected; or It can also be configured to determine whether there is a touch action by sensing the intensity of the ambient light incident thereon. For another example, the photoelectric sensing circuit 130 may be arranged in an array of m rows and n columns (m, n are integers), and the fingers formed by the ridge lines and the valley lines may be obtained by combining the sensing electrical signals output by the plurality of photoelectric sensing circuits 130. Fingerprint two-dimensional pattern to achieve fingerprint recognition.

For example, as shown in FIG. 3a, in one example, the photo sensing circuit 130 can include a photosensitive element 230 and an amplifying circuit 231. The photosensitive element 230 is configured to convert light incident thereon into a sensing electrical signal; the amplifying circuit 231 is configured to amplify the sensing electrical signal output by the photosensitive element 230, whereby the sensing electrical signal of the photoelectric sensing circuit 130 can be boosted Signal to noise ratio. That is, the pixel circuit 100 provided by the embodiment of the present disclosure can ensure or enhance the signal-to-noise ratio of the sensing electrical signal while optimizing the circuit layout.

For example, the photosensitive element 230 may include a photodiode PD that can sense the intensity of light incident thereon and cause a change in the reverse current of the photodiode PD. For example, the photodiode PD may include a PN junction type photodiode, a PIN junction type photodiode, an avalanche type photodiode, and a Schottky type photodiode. It should be noted that the photosensitive element 230 may also include other suitable devices, such as metal-oxide-metal structure electrical contact photodiodes, phototransistors, and the like.

For example, the photo sensing circuit 130 may further include a first node N1, and the amplifying circuit 231 may include a source follower transistor M8. The source follower transistor M8 includes a control electrode, a first pole and a second pole, and the photodiode PD includes a first end and a second end. For example, the first node N1 is disposed between the gate of the source follower transistor M8 and the second end of the photodiode PD. The first end of the photosensitive element 230 is connected to the bias voltage terminal VBIAS, and the second end thereof is connectable to the first node N1. The second end of the photosensitive element 230 is configured to control the gate of the source follower transistor M8. The gate of the source follower transistor M8 is also connected to the first node N1, and the first pole of the source follower transistor M8 can be set as the sense signal output b1 of the photo-sensing circuit 130, that is, the first pole of the source follower transistor M8 It may be used to connect with the third terminal a3 of the illumination control circuit 120 to receive a constant predetermined current transmitted from the illumination control circuit 120, and the first pole of the source follower transistor M8 is also connected to the signal line 140 at the same time to output the sensing. The second pole of the source follower transistor M8 can be set as the inductive voltage access terminal b2 of the photosensor circuit 130, and the inductive voltage access terminal b2 is connected to the second power source terminal V2, that is, the source follows The second pole of the transistor M8 can be connected to the second power terminal V2 to receive the second power voltage signal output by the second power terminal V2.

For example, as shown in FIG. 3a, in one example, the photo-sensing circuit 130 can also include a reset circuit 232. The output of reset circuit 232 is coupled between photosensor 230 and amplifier circuit 231 and is configured to reset the voltage of the output node of photodiode PD (e.g., corresponding to first node N1 in Figure 3a). The reset circuit 232 may include a reset transistor M9, the control electrode of the reset transistor M9 is configured to receive the reset signal RST1, the first pole of the reset transistor M9 is connected to the first node N1, and the second pole of the reset transistor M9 is connected to the reset power terminal VRST1. To receive the reset voltage, the first pole of the reset transistor M9 can be set as the output of the reset circuit 232.

For example, as shown in FIG. 3b, in another example, the photo-sensing circuit 130 may further include a buffer switch circuit 233 disposed between the photosensitive element 230 and the amplifying circuit 231 and configured to control the photosensitive element The 230 and the amplifying circuit 231 are turned on or off, so that it can be used to control whether or not the sensing electric signal generated by the photodiode PD in response to the incident light is output.

For example, the buffer switch circuit 233 may include a buffer transistor M11 having a first pole connected to the first node N1, a second pole connected to the second end of the photodiode PD, and a control pole for receiving the buffer control signal TX . The buffer transistor M11 can buffer the sensing electrical signal generated by the photodiode PD and then follow the gate of the source follower transistor M8, so that the signal-to-noise ratio of the sensing electrical signal can be improved.

For example, in the case where the photo-sensing circuit 130 includes the photodiode PD, the source follower transistor M8, the reset transistor M9, and the buffer transistor M11, the photo-sensing circuit 130 can implement touch detection and/or fingerprint recognition functions by the following operations:

S110: in the reset phase, the reset transistor M9 is turned on, and the reset voltage is written to the first node N1 via the reset transistor M9;

S120: in the photoelectric conversion phase, the reset transistor M9 is in an off state, and the buffer transistor M11 is in an off state, and the photodiode PD generates and accumulates a sensing electrical signal;

S130: The signal reading phase is such that the buffer transistor M11 is in an on state to write the sensing electrical signal to the first node N1, and the third terminal a3 of the illumination control circuit 120 is the source follower transistor M8. A pole provides a constant predetermined current such that the sense voltage on the first node N1 follows the first pole of the source follower transistor M8 and then reads the first pole on the source follower transistor M8 via the signal line 140. Sense voltage.

For example, in operation S110, the reset signal RST1 becomes a low level, and the buffer control signal TX remains at a high level. At this time, the reset transistor M9 is turned on, and the buffer transistor M11 is turned off, so that the voltage of the first node N1 can be set to the reset voltage. For example, the reset voltage can be a reference voltage and the reference voltage can be a high level signal.

For example, in operation S120, when a touch operation or fingerprint recognition is performed, the reset signal RST1 becomes a high level, and the buffer control signal TX is also at a high level. Thereby, both the buffer transistor M11 and the reset transistor M9 are in an off state, and the light emitted by the light source (for example, the light emitting element EL) is reflected by, for example, a finger, and when irradiated onto the photodiode PD, the photon is excited to be on the PN junction of the photodiode. An electron hole pair is generated, whereby the photodiode PD responds to the incident light and performs photoelectric conversion to generate a sensing electrical signal, and the sensing electrical signal accumulates on the photodiode PD to generate a voltage.

For example, in operation S130, the reset signal RST1 is maintained at a high level, and the buffer control signal TX is changed to a low level, so that the buffer transistor M11 is turned on. At this time, the sensing electrical signal can be written to the first node N1 via the buffer transistor M11, the voltage of the first node N1 is lowered, and a constant predetermined current outputted by the third terminal a3 of the light emission control circuit 120 can be applied to The source follows the first pole of transistor M8 such that the sense voltage on first node N1 follows the gate of source follower transistor M8 to its first pole and is thus read by signal line 140.

For example, in the reset phase, the third terminal a3 of the illumination control circuit 120 can be applied with a constant predetermined current to the first pole of the source follower transistor M8, causing the reset voltage to follow from the gate of the source follower transistor M8 to its first The reset voltage is then read through the signal line 140, and the reset voltage can be a reference voltage, and the sensed electrical signal can be obtained by making a difference between the reference voltage and the sense voltage. For another example, the reference voltage may be set in advance in the signal reading circuit.

For example, the magnitude of the sensed electrical signal depends on the magnitude of the voltage of the gate of the source follower transistor M8 (ie, the voltage of the first node N1), and the magnitude of the voltage of the gate of the source follower transistor M8 depends on the phase of the photoelectric conversion. The accumulated value (integral value) of the electrical signal of the middle photodiode PD, that is, the intensity of light incident on the photodiode PD. Thereby, fingerprint recognition can be performed by combining the sensing electrical signals output by the plurality of photodiodes PD; or, whether the corresponding position of the pixel circuit 100 exists at the corresponding position according to the magnitude of the sensing electrical signals output by the photodiode PD Touch operation. For example, compared to the absence of a touch operation, in the case where there is a touch operation, the voltage of the first node N1 is lower, and thus the sensing electrical signal acquired by the signal line 140 in the signal reading phase is larger. In this case, if the sensing electrical signal acquired by the signal line 140 is greater than a predetermined value, it is determined that there is a touch operation at a corresponding position of the pixel circuit 100; and the sensing electrical signal outputted by the photodiode PD is less than or equal to a predetermined value. In the case of the pixel circuit 100, it is determined that there is no touch operation at the corresponding position of the pixel circuit 100. For example, the predetermined value can be obtained based on experimental measurements. Thus, the display panel including the pixel circuit 100 can implement the functions of touch detection and/or fingerprint recognition.

For example, the illumination control circuit 120 provided by the embodiment of the present disclosure will be described in detail below with reference to FIGS. 4a and 4b. In the embodiment of the present disclosure, the illumination control circuit 120 can be implemented in various forms, such as a general 2T1C illumination control circuit, and other types of illumination control circuits that can be developed on the basis of these, and the illumination control circuit can further have a compensation function. Wait.

For example, as shown in FIG. 4a, the illumination control circuit 120 can be coupled to the illumination element 110 and configured to drive the illumination element 110 to emit light. The illumination control circuit 120 can include a first end a1, a second end a2, and a third end a3. The first end a1 is for connection with the first power terminal V1, the second end a2 is for connecting with the first end c1 of the light-emitting element 110, and the third end a3 is for connecting with the sensing signal output terminal b1 of the photo-sensing circuit 130.

For example, the light emission control circuit 120 may include a light emission driving circuit 121, a light emission selection circuit 122, and a first capacitance C1. The light emitting driving circuit 121 is configured to control a current for driving the light emitting element 110 to pass between the first end a1 and the second end a2, and the light emitting driving circuit 121 is further configured to control the first end a1 and the third end a3 The current passing through; the light emission selection circuit 122 is configured to write the light emission data voltage to the control terminal of the light emission driving circuit 121; the first capacitance C1 may be configured to store the light emission data voltage and maintain it in the control of the light emission driving circuit 121 end. It should be noted that the specific forms of the light-emitting driving circuit 121, the light-emitting selection circuit 122, and the first capacitor C1 may be set according to actual application requirements, which is not specifically limited in the embodiment of the present disclosure.

For example, in one example, as shown in FIG. 4a, the illumination control circuit 120 further includes a lighting switch circuit 123. The light-emitting switch circuit 123 is disposed between the light-emitting drive circuit 121 and the light-emitting element 110, and is configured to control the light-emitting drive circuit 121 and the light-emitting element 110 to be turned on or off.

For example, in one example, as shown in FIG. 4a, the illumination control circuit 120 further includes a light sensing switch circuit 124. The light sensing switch circuit 124 is disposed between the light emitting driving circuit 121 and the photo sensing circuit 130, and is configured to control to turn on or off the light emitting driving circuit 121 and the photo sensing circuit 130.

For example, in the example shown in FIG. 4a, the illumination control circuit 120 can be implemented as a 4T1C circuit, and an illumination switch circuit and a photo-sensing switch circuit are added to the conventional 2T1C circuit, that is, four TFTs (Thin-film transistors) are used. The transistor and a storage capacitor are used to implement the basic function of driving the light-emitting element 110 (for example, OLED) to emit light, and the photoelectric sensing circuit 130 can also be controlled to output a sensing electrical signal to implement the functions of touch detection and fingerprint recognition.

For example, as shown in FIG. 4a, a 4T1C type illumination control circuit 120 may include a fifth transistor M5 (ie, illumination selection circuit 122), a third transistor M3 (ie, illumination driving circuit 121), and a sixth transistor M6 (ie, The light-emitting switch circuit 123), the light-sensitive switching transistor M7 (ie, the light-sensitive switch circuit 124), the first capacitor C1, the second node N2, and the third node N3. For example, the control electrode of the fifth transistor M5 can receive the scan signal Gate, the first pole of the fifth transistor M5 can be electrically connected to the data signal terminal Vdata to receive the illuminating data voltage _Vdata1 , and the second pole of the fifth transistor M5 can be connected. Go to the second node N2. For example, the control terminal of the third transistor M3 may be connected to the second node N2, the first electrode of the third transistor M3 may be connected to the third node N3, and the second electrode of the third transistor M3 may be connected to the first power supply terminal V1. For example, the first end of the first capacitor C1 is connected to the second node N2 (ie, between the second pole of the fifth transistor M5 and the gate of the third transistor M3), and the second end of the first capacitor C1 is connected to the A power terminal V1. For example, the control electrode of the sixth transistor M6 can receive the second output signal EM2, and the first electrode of the sixth transistor M6 can be connected to the first end c1 of the light emitting element 110 (eg, the positive terminal of the OLED), and the sixth transistor M6 The second pole is also connected to the third node N3, that is, to the first pole of the third transistor M3; the second end c2 of the light emitting element 110 (for example, the negative terminal of the OLED) is connected to the second power terminal V2. For example, the control electrode of the photo-sensitive switching transistor M7 can receive the first output signal EM1, the first pole of the photo-sensitive switching transistor M7 is connected to the sensing signal output terminal b1 of the photo-sensing circuit 130, and the second pole of the photo-sensitive switching transistor M7 is also Connected to the third node N3, that is, connected to the first pole of the third transistor M3.

For example, as shown in FIG. 2c and FIG. 4a, the control electrode of the photo-sensitive switching transistor M7 and the control electrode of the signal-reading switching transistor M10 may be connected to the same output signal line to receive the same first output signal EM1, or may be connected to The different output signal lines are synchronized with the first output signal EM1 applied by both.

For example, one of the first power terminal V1 and the second power terminal V2 is a high voltage terminal and the other is a low voltage terminal. For example, the first power terminal V1 may be a voltage source to output a constant positive voltage; and the second power terminal V2 may be a ground terminal.

For example, the 4T1C type illumination control circuit 120 is driven by controlling the brightness and darkness (gray scale) of the pixel via the four TFTs and the first capacitor C1. In the display phase, the scan signal Gate is applied through the gate line to turn on the fifth transistor M5, and the data driving circuit charges the first capacitor C1 via the fifth transistor M5 through the illuminating data voltage V _data1 fed through the data line, thereby emitting light. The data voltage V _{data1 is} stored in the first capacitor C1, and the stored illuminating data voltage V _data1 can control the conduction degree of the third transistor M3, thereby controlling the magnitude of the current flowing through the third transistor M3; the second output signal EM2 Is applied to the gate of the sixth transistor M6 to turn on the sixth transistor M6 while turning off the photo-sensitive switching transistor M7, so that the sixth transistor M6 can receive the illuminating current signal flowing through the third transistor M3, and The illuminating current signal is transmitted to the illuminating element 110 to drive its illuminating, and the current flowing through the third transistor M3 can determine the gray level of the pixel illuminating. In the photo-sensing phase, the first output signal EM1 is applied to the gate of the photo-sensitive switching transistor M7 to turn on the photo-sensitive switching transistor M7 while turning off the sixth transistor M6, so that the photo-sensitive switching transistor M7 can receive The predetermined current is transmitted by the three transistors M3, and the predetermined current is transmitted to the photoelectric sensing circuit 130 to control the photoelectric sensing circuit 130 to output the sensing electrical signal, thereby implementing the functions of touch detection and fingerprint recognition. The predetermined current can be, for example, a constant predetermined current.

For example, the embodiment of the present disclosure is described only with the illumination control circuit 120 being a 4T1C circuit, but the illumination control circuit 120 of the disclosed embodiment is not limited to the 4T1C circuit. For example, according to actual application requirements, the illumination control circuit 120 may further include an electrical compensation function to improve the display uniformity of the display panel including the pixel circuit 100. For example, the compensation function can be implemented by voltage compensation, current compensation or hybrid compensation. The illumination control circuit 120 with compensation function can be, for example, 4T2C, 6T1C and other illumination control circuits 120 with electrical compensation functions.

For example, the illumination control circuit 120 can also include a illumination compensation circuit 125. The illumination compensation circuit 125 is configured to compensate for the illumination drive circuit 120. The illumination compensation circuit 125 can be an internal compensation circuit or an external compensation circuit. FIG. 4b is a schematic circuit diagram of an illumination control circuit with a compensation function according to an embodiment of the present disclosure.

For example, as shown in FIG. 4b, the illuminating compensation circuit 125 is an internal compensation circuit, which may include a first transistor M1, a second transistor M2, a fourth transistor M4, and a second capacitor C2, and the illuminating compensation circuit 125 may compensate for the third The threshold voltage _{Vth of the} transistor M3 drifts.

5a to 5d are operational flows of the compensation method of the illumination control circuit shown in Fig. 4b. It should be noted that, in FIGS. 5a and 5c, setting a square (□) at the position of the transistor indicates that the transistor is in an on state, and setting a circle (○) at the position of the transistor indicates that the transistor is in an off state.

For example, as shown in FIGS. 5a and 5b, in the reset phase, the scan signal Gate, the power supply control signal EM, the first output signal EM1, and the second output signal EM2 are both at a high level, and the reset signal Reset is at a low level. Therefore, the first transistor M1 is turned on, and the remaining transistors are all in an off state. At this time, the first transistor M1 resets the voltage of the fourth node N4 to the initial voltage Vint. The initial voltage Vint is, for example, a low voltage signal.

For example, as shown in FIGS. 5c and 5d, in the compensation phase, the scan signal Gate becomes a low level, the reset signal Reset becomes a high level, and the power supply control signal EM, the first output signal EM1, and the second output signal EM2 are both Keep high. At this time, the second transistor M2 and the fifth transistor M5 are turned on, and the remaining transistors are in an off state. Thereby, the fourth node N4 is charged by the fifth transistor M5 until the voltage of the fourth node N4 is V _data1 + _Vth , and V _data1 is the light-emitting data voltage outputted by the data signal terminal Vdata, and V _th is the first The threshold voltage of the three transistor M3, which is stored in the second capacitor C2. At this time, the voltage of the gate electrode of the third transistor M3 is V _data1 + V _th .

In the subsequent lighting phase, the scan signal Gate becomes a high level, the reset signal Reset and the first output signal EM1 remain at a high level, and the power supply control signal EM and the second output signal EM2 become a low level. At this time, the first transistor M1, the second transistor M2, and the fifth transistor M5 are in an off state, and the fourth transistor M4 and the sixth transistor M6 are in an on state, and the third transistor (drive transistor) M3 is also in an on state. . Based on the saturation current formula of the third transistor M3, the illuminating current signal flowing through the third transistor M3 can be obtained:

Iout=K(V _GS –V _th ) ²

=K[V _data1 +V _th –V ₁ –Vth] ²

=K(V _data1 –V ₁ ) ²

In the above formula, V _GS is the voltage difference between the gate and the source of the third transistor M3, V ₁ is the first power supply voltage signal outputted by the first power supply terminal V1, and V _th is the threshold voltage of the third transistor M3. As can be seen by the above formulas the threshold voltage Vth of the output current Iout at this time has not the third transistor M3, and a first supply voltage only with the first power supply terminal V1 signal V output voltage V ₁ and the light emission data _DATAl . While the emission data voltage V _data1 by the data signal terminal Vdata direct transmission, regardless of which of the third transistor M3, the threshold voltage V _th, so that we can solve the third transistor M3 due to the process technology and the long operation causes the threshold voltage V _th drift The problem is to ensure the accuracy of the illuminating current signal.

For example, the illuminating compensation circuit 125 may also be an external compensation circuit. For example, the sensing circuit portion may be included to sense the electrical characteristics of the driving transistor or the electrical characteristics of the illuminating element. For details, refer to the conventional design, and details are not described herein again.

For example, in the embodiment of the present disclosure, by providing the photo sensing circuit 130 in the pixel circuit 100, the display panel including the pixel circuit 100 is provided with a touch detection and fingerprint recognition function; by the third end a3 of the illumination control circuit 120 The sensing signal output terminal b1 of the photo-sensing circuit 130 is connected, so that the photo-sensing circuit 130 can time-multiplex the predetermined current output by the light-emitting control circuit 120, whereby the structural layout of the pixel circuit 100 can be optimized. In the embodiment of the present disclosure, by providing the amplifying circuit 231 in the photo sensing circuit 130, the signal-to-noise ratio of the sensing electrical signal of the photo sensing circuit 130 can be ensured or improved in the case of optimizing the circuit layout.

It should be noted that the photoelectric sensing circuit can be replaced with other sensor circuits that need to work with a constant current source, thereby detecting other kinds of sensor signals.

An embodiment of the present disclosure provides a display panel, which further has a touch function or a fingerprint recognition function, etc., so that the functions of the electronic device using the display panel can be more diverse, the structure is more compact, and the like.

For example, as shown in FIG. 6a, the display panel 10 includes a plurality of pixel units 11 arranged in an array. For the sake of clarity, FIG. 6a exemplarily shows two rows and three columns of pixel units 11, but the embodiment of the present disclosure is not limited thereto. For example, according to actual application requirements, the display panel 10 may include 1440 rows and 900 columns. Pixel unit 11.

For example, at least one of the pixel units 11 includes the pixel circuit of any of the above. As shown in Fig. 6a, in the case where the pixel unit 11 includes the pixel circuit described in any of the above, the pixel unit 11 may include a light-emitting region 211 and a light-sensitive region 311. For example, as shown in FIG. 6a, the light-sensitive region 311 may be disposed between two adjacent light-emitting regions 211 in the row direction. However, embodiments of the present disclosure are not limited thereto, and the light-sensitive region 311 may also be disposed in the column direction. Between the two adjacent light-emitting regions 211, or between the adjacent four light-emitting regions 311. It should be noted that the arrangement manner, the area ratio, and the like of the light-emitting area 311 and the light-sensing area 211 can be set according to actual application requirements, and the embodiment of the present disclosure does not specifically limit this.

For example, as shown in FIG. 6b, the photosensitive area 211 may include a photoelectric sensing circuit, and the photoelectric sensing circuit may include a photosensitive element (for example, the photodiode PD in the embodiment of the above pixel circuit), an amplifying circuit (for example, the above pixel circuit) The source in the embodiment follows the transistor M8) and the reset circuit (for example, the reset transistor M9 in the embodiment of the above pixel circuit) and the like. The light emitting region 311 may include a light emitting element (for example, the light emitting element EL in the embodiment of the above pixel circuit) and a light emission control circuit, and the light emission control circuit may include a light emitting driving circuit (for example, the third transistor M3 in the embodiment of the above pixel circuit) a light-emitting selection circuit (for example, the fifth transistor M5 in the embodiment of the pixel circuit described above) and a capacitor (for example, the first capacitor C1 in the embodiment of the pixel circuit described above) and the like. For example, in one pixel unit 11, the photosensitive region 211 may include a plurality of photosensitive elements, that is, a plurality of photosensitive elements may correspond to one light emitting element, and the plurality of photosensitive elements may increase the sensing electrical signal, thereby improving touch detection and/or Or the accuracy of fingerprint recognition. The correspondence between the photosensitive element and the light-emitting element can be set according to actual requirements, which is not limited in this embodiment.

For example, according to the required precision of the touch detection and/or fingerprint recognition, one pixel unit may be selected among a plurality of (for example, ten) pixel units, and the pixel circuit described in any one of the above may be disposed in the pixel unit; Alternatively, in order to achieve pixel-level touch detection and/or fingerprint recognition accuracy, all pixel units 11 on the display panel 10 may include any of the pixel circuits described above. For example, at least one column of pixel units 11 of the display panel 10 includes any of the pixel circuits described above, and each of the at least one column of pixel units 11 can share the same signal line to reduce the number of signal lines and improve The aperture ratio of the pixel unit, for example, the sensing electrical signals output by the respective photoelectric sensing circuits in the column of pixel units 11 can be read in time to realize the touch detection and/or fingerprint recognition functions.

For example, display panel 10 may also include an output selection circuit. In the touch and/or fingerprint recognition phase, the output selection circuit is configured to output a first output signal to control the display panel 10 to implement touch detection and/or fingerprint recognition functions; in the display phase, the output selection circuit is configured to output The two output signals are used to control the display panel 10 to implement a normal display function. Take the pixel circuit shown in Figure 4a as an example. For example, if the first output signal EM1 is at a low level and the second output signal EM2 is at a high level, at this time, the photo-sensitive switching transistor M7 is turned on, and the sixth transistor M6 is turned off. The illumination control circuit 120 converts the fixed signal read voltage provided by the data signal terminal Vdata into a constant predetermined current, and then is transmitted to the photo-sensing circuit via the photo-sensitive switching transistor M7. At this time, the signal line can read the output of the photo-sensing circuit. The electrical signal is sensed such that the display panel 10 can implement touch detection and/or fingerprint recognition functions. For example, if the first output signal EM1 is at a high level and the second output signal EM2 is at a low level, at this time, the photo-sensitive switching transistor M7 is turned off, and the sixth transistor M6 is turned on. The light emission control circuit 120 converts the light emission data voltage supplied from the data signal terminal Vdata into an emission current signal, and then is transmitted to the light emitting element EL via the sixth transistor M6, so that the display panel 10 can realize the normal light emission display function.

It should be noted that the specific form of the output selection circuit may be set according to actual application requirements, which is not specifically limited in the embodiment of the present disclosure.

FIG. 7 is a cross-sectional structural diagram of a pixel unit of a display panel according to an embodiment of the present disclosure.

For example, one pixel unit of the display panel 10 may include a reset transistor 114 (for example, a reset transistor M9 in the embodiment of the above pixel circuit) provided on the base substrate 60, a photosensitive element 112, and an illumination switching transistor 115 (for example, the above The sixth transistor M6) and the light emitting element 110 in the embodiment of the pixel circuit.

For example, as shown in FIG. 7, the reset transistor 114 is a top gate type transistor, and may include an active layer 154, a first gate insulating layer GI1, a gate 134, a second gate insulating layer GI2, an interlayer insulating layer ILD, and a source. Pole/drain 144. For example, the photosensitive element 112 may include a positive electrode, a negative electrode, and a photo-sensitive layer disposed therebetween. A passivation layer PVX may be disposed between the photosensitive element 112 and the reset transistor 114. The second end of the photosensitive element 112 may be electrically connected to the source or drain 144 of the reset transistor 114 through a via penetrating the passivation layer PVX. The first end may be drawn from a via that passes through the passivation layer PVX and the planarization layer PLN and is led out by the lead 61, and is finally electrically connected to the bias voltage terminal. As can be seen from FIG. 7, both ends of the photosensitive element 112 can be connected to the backplane circuit through via holes to achieve electrical connection.

For example, as shown in FIG. 7, the light-emitting switching transistor 115 may also be a top-gate transistor, and may include an active layer 155, a first gate insulating layer GI1, a gate electrode 135, a second gate insulating layer GI2, and an interlayer insulating layer. ILD and source/drain 145. The light emitting element 110 may include a cathode 72, an anode 71, a light emitting layer 70 interposed therebetween, and a pixel defining layer PDL. A passivation layer PVX and a flat layer PLN may be disposed between the light emitting element 110 and the light emitting switch transistor 115, and the anode 71 of the light emitting element 110 may pass through a via hole penetrating the passivation layer PVX and the flat layer PLN and a source of the light emitting switching transistor 115 or The drain 145 is electrically connected.

For example, the layers of the reset transistor 114 and the light-emitting switching transistor 115 can be formed simultaneously. Thereby, the process flow of the display panel 10 can be simplified.

For example, the pixel unit further includes a spacer PS to maintain uniformity of the display panel 10. The material of the spacer PS may be a suitable material such as an ultraviolet (UV) hardening type acryl resin. The shape of the spacer PS may be a column shape, a spherical shape, or the like.

It should be noted that, for the sake of clarity, the pixel unit shown in FIG. 7 shows only the reset transistor 114, the photosensitive element 112, the light-emitting switching transistor 115, and the light-emitting element 110. The pixel unit may further include other structures, and the pixel unit may further include, for example, the remaining devices in the embodiment of the above pixel circuit, for example, a signal line, a light sensing switch circuit, or the like. I will not repeat them here.

An embodiment of the present disclosure provides a driving method of a pixel circuit according to any of the above.

For example, as shown in FIG. 8, the driving method of the pixel circuit may include the following operations:

S210: In the display stage, the illumination control circuit drives the light emitting element to emit light;

S220: In the photoelectric sensing phase, output a predetermined current from the third end of the illumination control circuit to the photo-sensing circuit, and then read an output signal of the photo-sensing circuit.

For example, in the display phase, the electrical connection between the photo-sensing circuit and the illuminating control circuit is disconnected, for example, the sixth transistor is turned on, and the photo-sensing switching transistor is turned off, so that the illuminating current signal generated by the illuminating control circuit is output to the illuminating An element that drives the light emitting element to emit light.

For example, in the photo-sensing phase, the electrical connection between the light-emitting element and the light-emitting control circuit is broken, for example, the sixth transistor is turned off, and the light-sensitive switching transistor is turned on, so that the predetermined current generated by the light-emitting control circuit is output to the photoelectric sensing. The circuit can read the output signal of the photoelectric sensing circuit through, for example, a signal line, thereby implementing touch detection and/or fingerprint recognition functions.

For example, a plurality of photo-sensing stages may be included, and the predetermined current output by the third end of the illumination control circuit is the same in a plurality of photo-sensing stages.

The above operations are not sequential, and it is not required to be accompanied by a photoelectric sensing phase in each display phase. In the case of satisfying the touch time precision, a photoelectric sensing phase can be set for every two or more display phases. This reduces power consumption.

For example, the timing chart for driving the pixel circuit can be set according to actual needs, which is not specifically limited in the embodiment of the present disclosure. For example, FIG. 9b is an exemplary timing diagram of a driving method of the pixel circuit shown in FIG. 9a. For example, the length of time of the photo-sensing phase as shown in FIG. 9b is less than the length of time of the display phase, but embodiments of the present disclosure are not limited thereto. For example, according to actual application requirements, the length of time of the photoelectric sensing phase and the length of the display phase may be equal; the length of the photoelectric sensing phase may also be equal to one-half or one-tenth of the length of the display phase.

For example, as shown in Figures 9a and 9b, in one example, the display phase may further include a first reset phase RT1, a compensation phase CT, and an illumination phase LT.

In the first reset phase RT1, the scan signal Gate, the power control signal EM, the first output signal EM1, the second output signal EM2, and the reset signal RST1 are both at a high level, and the reset signal Reset is at a low level, thereby being first Transistor M1 is turned on, and the remaining transistors are all turned off. At this time, the first transistor M1 resets the voltage of the third node N3 to the initial voltage Vint. The initial voltage Vint is a low voltage signal.

In the compensation phase CT, the scan signal Gate becomes a low level, the reset signal Reset becomes a high level, and the power supply control signal EM, the first output signal EM1, the second output signal EM2, and the reset signal RST1 are both maintained at a high level. At this time, the second transistor M2 and the fifth transistor M5 are turned on, and the remaining transistors are in an off state. Thereby, the third node N3 is charged by the fifth transistor M5 until the voltage of the third node N3 is V _data1 + _Vth , and V _data1 is the light-emitting data voltage outputted by the data signal terminal Vdata, and V _th is the first The threshold voltage of the three transistor M3, which is stored in the second capacitor C2. At this time, the voltage of the gate electrode of the third transistor M3 is V _data1 + V _th .

In the light-emitting phase LT, the scan signal Gate becomes a high level, the second output signal EM2 and the power supply control signal EM become a low level, and the first output signal EM1, the reset signal Reset, and the reset signal RST1 remain at a high level. At this time, the third transistor T3, the fourth transistor M4, and the sixth transistor M6 are turned on, and the remaining transistors are in an off state. Thereby, the light-emission current signal flowing through the third transistor T3 is transmitted to the light-emitting element EL through the sixth transistor M6, thereby driving the light-emitting element EL to emit light corresponding to the light-emitting data voltage.

Based on the saturation current formula of the transistor, the illuminating current signal flowing through the third transistor M3 can be obtained:

Iout=K(V _GS –V _th ) ²

=K[V _data1 +V _th –V ₁ –Vth] ²

=K(V _data1 –V ₁ ) ²

It can be seen from the above equation that the output current Iout is no longer affected by the threshold voltage _Vth of the third transistor M3. That is, the current Iout that drives the light-emitting element EL to emit light is not affected by the threshold voltage _Vth of the third transistor M3, whereby the light-emission control circuit can compensate for the threshold voltage _Vth drift of the third transistor M3.

In the light emitting phase, the first output signal EM1 is kept at a high level, so that the light sensing switching transistor M7 is in an off state, that is, the light emitting current signal generated by the light emitting control circuit cannot be transmitted to the photoelectric sensing circuit, thereby the signal line cannot read the photoelectric sensing. The sensing electrical signal output by the circuit, the pixel circuit realizes the normal display function.

For example, as shown in Figures 9a and 9b, in one example, the photo-sensing phase includes a second reset phase RT2, a compensated reset phase CRT, and a signal read phase SRT.

For example, the second reset phase RT2 is the same as the first reset phase RT1 in the display phase, and details are not described herein again.

In the compensation reset phase CRT, the scan signal Gate and the reset signal RST1 become a low level, the reset signal Reset becomes a high level, and the power supply control signal EM, the first output signal EM1, and the second output signal EM2 are both maintained at a high level. . At this time, the second transistor M2 and the fifth transistor M5 are turned on, whereby the third node N3 is charged by the fifth transistor M5, and is charged until the voltage of the third node N3 is V _data2 + V _th , V _data2 The signal read voltage for the data signal terminal Vdata, _Vth is the threshold voltage of the third transistor M3, and the voltage is stored in the second capacitor C2. At this time, the voltage of the gate electrode of the third transistor M3 is V _data2 + V _th . At the same time, the reset transistor M9 is turned on to write the reset voltage on the first node N1 through the reset transistor M9, the reset voltage may be a reference voltage, and the reference voltage may be a high level signal. During this phase, the remaining transistors are in an off state.

For example, the signal read voltage V _data2 remains unchanged during each photo-sensing phase, thereby obtaining a stable predetermined current at the third end of the illumination control circuit; or the signal read voltage V _{data2 is} varied as needed during each photo-sensing phase. Thereby obtaining a desired predetermined current at the third end of the illumination control circuit.

In the signal reading phase SRT, the scan signal Gate and the reset signal RST1 become a high level, the power supply control signal EM and the first output signal EM1 become a low level, and the reset signal Reset and the second output signal EM2 remain at a high level. . At this time, the third transistor T3 and the fourth transistor M4 are turned on, and the light emission control circuit converts the signal read voltage V _data2 transmitted by the data signal terminal Vdata into a constant predetermined current and transmits it to the third terminal a3, and the light sensing switch The transistor M7 is turned on, so that the predetermined current outputted by the third end a3 of the illumination control circuit can be transmitted to the sensing signal output terminal b1 of the photo-sensing circuit via the photo-sensitive switching transistor M7, so that the sensing electrical signal generated by the photosensitive element PD can pass through the source. The pole follower transistor M8 follows to the sense signal output b1, and then the sensed electrical signal is read through the signal line 140.

It should be noted that the signal reading phase SRT in FIG. 9b only indicates the timing when the sensing electrical signals of the photo sensing circuits in one sub-pixel are read. For example, each photo sensing stage may include a plurality of signal reading stages SRT to time-read the sensing electrical signals of the photo-sensing circuits of the plurality of different sub-pixels.

In the photo-sensing phase, the second output signal EM2 is kept at a high level, so that the sixth transistor M6 is in an off state, that is, a predetermined current generated by the light-emission control circuit cannot be transmitted to the light-emitting element EL, whereby the light-emitting element EL does not emit light, and the pixel circuit Implement touch detection and/or fingerprint recognition.

The photoelectric sensing circuit in the pixel circuit provided by at least one embodiment of the present disclosure adopts an active detection method, and time-multiplexes a constant predetermined current generated by the illumination control circuit, thereby realizing high-precision sensing electrical signal detection and improving sensing. The signal-to-noise ratio of the electrical signal; at the same time, the space occupied by the photoelectric sensing circuit is reduced, the structural layout of the pixel circuit is optimized, the manufacturing cost is saved, and the added value of the product is improved.

It will be apparent to those skilled in the art that various changes and modifications can be made in the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present invention cover the modifications and the modifications

The above is only an exemplary embodiment of the present disclosure, and is not intended to limit the scope of the disclosure. The scope of the invention is defined by the appended claims.

Claims

A pixel circuit comprising: a light emitting element, a light emitting control circuit, and a photoelectric sensing circuit, wherein

The illumination control circuit is configured to drive the light emitting element to emit light and includes a first end, a second end, and a third end, the first end for connecting to a first power end, and the second end for The light emitting elements are connected;

One end of the light emitting element is connected to the second end of the light emitting control circuit, and the other end is used for connecting with the second power end;

The photoelectric sensing circuit is configured to sense light incident thereon and includes an inductive signal output end and an inductive voltage access end, wherein the inductive voltage access end is configured to be connected to the second power end, the sensing The signal output is for connecting to the third end of the illumination control circuit.
The pixel circuit according to claim 1, further comprising a signal line,

The signal line is configured to receive a signal output by the sensing signal output end of the photoelectric sensing circuit.
The pixel circuit according to claim 2, further comprising a signal reading switch circuit,

Wherein the signal line includes a first portion and a second portion, the signal read switch circuit is disposed between the first portion and the second portion, and is configured to control the first portion and the first portion The two portions are turned on or off, and the first portion is for connecting to the sensing signal output end of the photoelectric sensing circuit.
The pixel circuit of any of claims 1-3, wherein the illumination control circuit comprises:

An illumination driving circuit configured to control a current passing between the first end and the second end for driving illumination of the light emitting element and for controlling the first end and the third end Current passing between;

a light emitting selection circuit configured to write a data signal to a control end of the light emitting driving circuit;

A capacitor configured to store the data signal and maintain it at a control end of the illumination driving circuit.
The pixel circuit according to claim 4, wherein said light emission control circuit further comprises a light sensing switch circuit,

The light sensing switch circuit is disposed between the light emitting driving circuit and the photoelectric sensing circuit, and is configured to control to turn on or off the light emitting driving circuit and the photoelectric sensing circuit.
A pixel circuit according to claim 4 or 5, wherein said illumination control circuit further comprises a illumination compensation circuit configured to compensate said illumination drive circuit.
A pixel circuit according to any one of claims 4-6, wherein said light emission control circuit further comprises a light switch circuit,

The light emitting switch circuit is disposed between the light emitting driving circuit and the light emitting element, and is configured to control to turn on or off the light emitting driving circuit and the light emitting element.
The pixel circuit according to any one of claims 1 to 7, wherein the photo sensing circuit comprises a photosensitive element and an amplifying circuit,

The photosensitive element is configured to convert light incident thereon to a sensing electrical signal, the amplification circuit configured to amplify the sensing electrical signal output by the photosensitive element.
The pixel circuit according to claim 8, wherein said amplifying circuit comprises a source follower transistor, said source follower transistor comprising a gate, a first pole and a second pole,

One end of the photosensitive element is connected to the bias voltage terminal and the other end is arranged to control the control electrode of the source follower transistor, and the first pole of the source follower transistor is connected to the sensing signal output end of the photoelectric sensing circuit The second pole of the source follower transistor is coupled to the inductive voltage access terminal of the photo-sensing circuit.
The pixel circuit according to claim 8 or 9, wherein said photo sensing circuit further comprises a reset circuit,

An output of the reset circuit is coupled between the photosensitive element and the amplifying circuit and is configured to reset an output signal of the photosensitive element.
The pixel circuit according to any one of claims 8 to 10, wherein the photoelectric sensing circuit further comprises a buffer switch circuit,

The snubber switch circuit is disposed between the photosensitive element and the amplifying circuit and configured to control conduction or disconnection of the photosensitive element and the amplifying circuit.
A display panel comprising an array of pixel units, wherein at least one of the pixel units comprises a pixel circuit according to any of claims 1-11.
A method of driving a pixel circuit according to any one of claims 1-11, comprising:

In the display phase, the illumination control circuit drives the light emitting element to emit light;

In the photo-sensing phase, a predetermined current is output from the third end of the illumination control circuit to the photo-sensing circuit, and then an output signal of the photo-sensing circuit is read.
The driving method according to claim 13, wherein in the display phase, an electrical connection between the light emission control circuit and the photoelectric sensing circuit is broken.
The driving method according to claim 13 or 14, comprising a plurality of photo-sensing stages such that said predetermined current outputted by said third end of said light-emission control circuit is the same in said plurality of photo-sensing stages.